The present invention relates to a method for operating a navigation system for a vehicle, particularly for a motor vehicle.
It is known to equip motor vehicles with navigation systems which are able to make available to the vehicle driver, a travel route in the form of an acoustical or visual message. To calculate the travel route, the navigation system generally falls back on a digitally stored map which also contains a structure of a road type (e.g. expressway or country road). Furthermore, a travel destination and location of the motor vehicle should be known. The travel destination is entered into the navigation system by the vehicle driver via a suitable input device. The location can be determined in a known manner, for example, by radio location. With the aid of these inputs, the travel route with the least travel time can be determined in a simple manner.
To additionally take the instantaneous traffic situation into account, it is also known to continuously acquire traffic information via a receiver unit (e.g. as RDS/TMC or GSM signals). The traffic information contains details about the type of traffic disturbance (disturbance event), for example, traffic jam, halting, dense or busy traffic, as well as about the length of the traffic disturbance. In known navigation systems, the disturbance event is taken into account in the form of a weighting factor which is multiplied by an average speed otherwise possible on this type of road. Thus, a new travel time for the existing travel route is yielded on the basis of the length of the traffic disturbance. This travel time is continuously compared to a travel time for at least one alternative route, and in the event that the travel time of the alternative route is shorter than the travel time of the travel route, the alternative route is indicated to the vehicle driver.
Disadvantageous in such a method is that it does not adequately take into account a subjective feeling of the vehicle driver with respect to the traffic disturbance to be expected. Thus, as is known, different vehicle drivers feel extremely differently about the same traffic disturbance. For example, for many vehicle drivers, driving in a traffic jam represents a stress situation which they would avoid, even putting up with a longer travel time overall.
According to the present invention, a method is provided for operating the navigation system. Because a correction value K is ascertained for weighting factors Gf in light of the length of the traffic disturbance Ls, and a corrected weighting factor Gk, used to calculate new travel time t, is ascertained as a function of correction value K, it is possible to adapt the navigation system individually to the subjective feeling of the vehicle driver. In particular, the subjective feeling of the vehicle driver may be suitably taken into account when calculating alternative routes.
Correction value K may be determined with the aid of a family of characteristics or a predefined formula. Thus, corrected weighting factor Gk can preferably be determined according to the formula
Gk=Gfxe2x88x92K
with K=Ls/n*100,
where nxe2x89xa71, and in the event that Gk becomesxe2x89xa60, an alternative route is automatically calculated. Because the vehicle driver determines the value for n, it is possible to take his/her subjective feeling with respect to the length of the traffic disturbance Ls into consideration.